Type IV collagen and laminin staining patterns in benign and malignant cutaneous lesions.

The presence of both laminin and type IV collagen was sought at the dermo-epidermal junction and in the dermis adjacent to benign melanocytic naevi of the junctional, compound, and intradermal types; dysplastic naevi; and both primary and secondary melanoma. In all, 154 lesions were studied, using antibodies to laminin and type IV collagen and an indirect immunoperoxidase technique. The staining patterns seen with the two antibodies were virtually identical, although that of laminin was generally fainter. Breaks in and thinning of the normally continuous line of type IV collagen and laminin at the dermo-epidermal junction were seen in association with the junctional activity of benign naevi, and in malignant melanomas in association with invasive tumour cells. Both benign and malignant cells of the melanocyte series showed relatively light pericellular staining around individual cells and clusters of cells in the papillary dermis. This staining pattern was much stronger in the deeper reticular dermis. It is concluded that the pattern of staining of these two antibodies and in particular the presence of breaks in type IV collagen and laminin at the dermo-epidermal junction are not specific for either benign or malignant melanocytic lesions and cannot be used as a diagnostic marker of invasive malignancy.